Log Message:
databases/php-mongodb: update to 1.17.2

Drop php56 and support php74 and later.

Currently, it dose not use databases/mongo-c-driver but use bundled
libraries since we don't have databases/libmongocrypt package yet(?).

Changes from 1.9.1 is too many to write here, please refer
<https://pecl.php.net/package-changelog.php?package=mongodb>.